Various Cheats:
Just enter these passwords

EPS Get Championship Mode
PBR Slalom
PDL Get Hidden Track
BIF Get Fast Boats
BAD Get Slow Boats
FAN Catamarans (Minnow)
DIP Catamarans (Pike)
URN Catamarans (Barracuda)

Name Cheats:
Enter these cheats for your name

SML Tiny Boat Mode
BIG Get Big Head Mode
POW Get Big Engine Mode
BAA Auto Pilot
WIN Always Win